The Low FODMAP Diet

Irritable Bowel Syndrome

Irritable Bowel Syndrome or otherwise known as IBS is described as maybe the most common reason for visiting a gastroenterologist. It is estimated that it significantly affects the quality of life of about 10-20% of the general population (1).

Symptoms characterizing the IBS are:


• Alterations in bowel habits like diarrhea or constipation

• Cramping,

• Gas,

• Gastrocoli reflex (2)

Gastrocolic reflex is characterizing the meal-induced motor activity of the large intestine. Gastrocolic reflex causes strong mass peristalsis movements that lead feces into the rectum. (3).

As mentioned earlier, although many people suffer of IBS, research has not managed to eliminate yet this syndrome. However, researchers have proposed possible mechanisms to explain how the syndrome works. These mechanisms include altered gut microbiota, abnormal gut motility, visceral hypersensitivity and central sensitization (4).

There are 4 types of IBS:

•IBS  with constipation

• IBS with diarrhea

• mixed IBS with both constipation and diarrhea

• IBS without diarrhea or constipation (5).

It is almost 60-70 % of the IBS patients that identify food as the triggering factor for their symptoms. It is not only the type of food but also the amount that can cause the above-mentioned symptoms. Some of the most usual foods that lead to IBS symptoms include wheat, cabbage, beans and other high fiber foods, and dairy products. It is important to highlight at this point that the presence of high- fat concentrations results in diarrhea (6).

Latest research on IBS suggests a diet low in FODMPS for IBS symptom improvement.


According to the Monash University-Australia, FODMAPs are a group of carbohydrates that are not fully digested in our intestines. When they get to the small intestine, they move slowly, attracting water. Then they get into the large intestine, and they are fermented by gut bacteria, producing gas. It is this gas and the water that causes symptoms like the intestinal wall to stretch and expand and leading to pain and discomfort (7). FODMAPS are found in many widely consumed foods like fruits, vegetables, wheat, and other grains, some dairy products.


The low FODMAP diet is a 2-periods intervention, with initially a reduction of all dietary FODMAPs which is followed by the reintroduction of specific FODMAPs according to tolerance to determine the personal FODMAP sensitivities.

The target of the low FODMAP diet is to limit the intake of foods rich in FODMAPS to avoid the caused symptoms.

Common foods, high in FODMAPS that should be limited (7,8)
Nuts like pistachios and cashews
Dairy like milk and yogurt
Fruit juices
High fructose corn syrup and products that include it
Sweets like biscuits and other packaged snack products
Chickpeas, onion, cauliflower, garlic
Apples, watermelon, dried fruit,
Wheat, breakfast cereals
Sugar substitutes such as mannitol, sorbitol, xylitol

To be able to have a diet providing all the necessary nutrients, the consumption of a variety of low FODMAP foods is required. Nowadays, there are plenty of low FODMAP alternatives that can make your dishes tasty and provide a high quality of nutrients.

Common foods, low in FODMAPS that should be consumed (7)
Almond milk, feta cheese, lactose-free milk
Oats, quinoa flakes, rice cakes
Sweets and sweeteners like dark chocolate, and table sugar
Fruits like kiwi, orange, strawberries, and grapes
 Seafood, poultry
 Eggs, tofu
 Nuts like peanuts, walnuts, macadamias
 Vegetables like carrot, zucchini, eggplant, green beans, tomato, lettuce, cucumber, capsicum

Effectiveness of the low FODMAP diet

A study in the UK has shown that a low FODMAP diet had better results compared to the UK national guidelines in IBS management. In addition, there is an Australian study concluding that patients with IBS had fewer and less intense gastrointestinal symptoms while being on a diet low in FODMAPs, compared to the Australian diet (9).

In a 2019 published study researchers worked on the effects of FOODMAPs on quiescent inflammatory bowel disease symptoms for 4 weeks. After the 4 -weeks of intervention they concluded that a 4-week diet that is low in FODMAPs, can be safe and reduce persistent gut symptoms in patients with inflammatory bowel disease (10).

In another 2019 study, Irish researchers investigated the effects of the FODMAP diet in patients with IBS over a 12-month follow-up period, including the period of re-introduction of the high FODMAP foods. Results showed that a low FODMAP diet can significantly improve all IBS symptoms at 3-, 6-, and 12-month follow-up, thus it can be used for longer- term than 3 months and maintain the same positive symptom-related results (11).

In a (2017) study among patients with  IBS, researchers evaluated the effect of low FODMAP diet and IBS symptoms. They found that low FODMAP diet leads to symptom relief and significant reduction of the symptoms compared to the placebo. Moreover, since there is evidence that a low FODMAP diet leads to a reduction in gastrointestinal microbiota, researchers investigated whether the low FODMAP diet-induced alterations in the microbiota could be prevented through supplementation of probiotics. They reported that the co-administration of a multistrain probiotic increases the microbiota, thus a probiotic supplementation is beneficial during the low FODMAP diet (12).

In relation to the above-mentioned comment about the risk of alterations of the gut microbiota, while following a low FODMAP diet, there is a 2019 published study reporting that “the low-FODMAP diet leads to a considerably reduced intake of prebiotic fructans and galactooligosaccharides “.  Furthermore, FODMAPs play a role in the synthesis of short-chain fatty acids. Therefore, significant dietary restrictions of FODMAPs can potentially lead to nutritional deficiencies (13). An additional study supports that a strict, low FODMAP diet is not recommended for a period longer than 8-week and a balanced, less restrictive diet should be followed afterward to limit the chances of nutrient deficiencies and most important to avoid the possible change of the gut bacteria (14).

Take away message

To sum up, symptoms that characterize the disturbed gastrocolic reflex, are closely related to autoimmune and inflammatory diseases like Crohn’s Disease, Ulcerative Colitis, and Irritable Bowel Syndrome. Diet plays a key role in the prevention and relief of the above-mentioned conditions and their symptoms. The low FODMAP diet does not cure Irritable Bowel Syndrome, but it is a useful tool that can help you reduce the symptoms and improve your daily quality of life. The low FODMAP diet does not work for all the patients because of the number of disorders and mechanisms involved in the causal of the illness, but when you follow it strictly you increase the chances of success. The supplementary intake of probiotics may have a positive role and improve gastrointestinal health while following the low FODMAP diet. Quality and consumption of a variety of foods are crucial for the safety and long-term compliance of the patient on the low FODMAP diet.


1) Lovell, R. and Ford, A., 2012. Global Prevalence of and Risk Factors for Irritable Bowel Syndrome: A Meta-analysis. Clinical Gastroenterology and Hepatology, 10(7), pp.712-721.e4.

2) Bouchoucha, M., Odinot, J., Devroede, G., Landi, B., Cugnenc, P. and Barbier, J., 1998. Simple clinical assessment of colonic response to food. International Journal of Colorectal Disease, 13(5-6), pp.217-222.

3) Rao, S., 2000. Effects of fat and carbohydrate meals on colonic motor response. Gut, 46(2), pp.205-211.

4) Drug and Therapeutics Bulletin, 2015. Does a low FODMAP diet help IBS?:. 53(8), pp.93-96.

5) Rajilić-Stojanović, M., Jonkers, D., Salonen, A., Hanevik, K., Raes, J., Jalanka, J., de Vos, W., Manichanh, C., Golic, N., Enck, P., Philippou, E., Iraqi, F., Clarke, G., Spiller, R. and Penders, J., 2015. Intestinal Microbiota And Diet in IBS: Causes, Consequences, or Epiphenomena?. American Journal of Gastroenterology, 110(2), pp.278-287.

6) Deiteren, A., Camilleri, M., Burton, D., McKinzie, S., Rao, A. and Zinsmeister, A., 2009. Effect of Meal Ingestion on Ileocolonic and Colonic Transit in Health and Irritable Bowel Syndrome. Digestive Diseases and Sciences, 55(2), pp.384-391.

7) n.d. About Fodmaps And IBS | Monash FODMAP – Monash Fodmap. [online] Available at: <> [Accessed 13 July 2020].

8) Digestive Health Foundation . Information about Low Fodmap Diet to improve Irritable Bowel Syndrome (IRS) symptom control. Second edition 2013

Barrett J,Iannelli L, Halmos E

9) Halmos, E., Power, V., Shepherd, S., Gibson, P. and Muir, J., 2014. A Diet Low in FODMAPs Reduces Symptoms of Irritable Bowel Syndrome. Gastroenterology, 146(1), pp.67-75.e5.

10) Cox, S., Lindsay, J., Fromentin, S., Stagg, A., McCarthy, N., Galleron, N., Ibraim, S., Roume, H., Levenez, F., Pons, N., Maziers, N., Lomer, M., Ehrlich, S., Irving, P. and Whelan, K., 2020. Effects of Low FODMAP Diet on Symptoms, Fecal Microbiome, and Markers of Inflammation in Patients With Quiescent Inflammatory Bowel Disease in a Randomized Trial. Gastroenterology, 158(1), pp.176-188.e7.

11) Nawawi, K., Belov, M. and Goulding, C., 2019. Low FODMAP diet significantly improves IBS symptoms: an Irish retrospective cohort study. European Journal of Nutrition, 59(5), pp.2237-2248.

12) Staudacher, H., Lomer, M., Farquharson, F., Louis, P., Fava, F., Franciosi, E., Scholz, M., Tuohy, K., Lindsay, J., Irving, P. and Whelan, K., 2017. A Diet Low in FODMAPs Reduces Symptoms in Patients With Irritable Bowel Syndrome and A Probiotic Restores Bifidobacterium Species: A Randomized Controlled Trial. Gastroenterology, 153(4), pp.936-947.

13) Paduano, D., Cingolani, A., Tanda, E. and Usai, P., 2019. Effect of Three Diets (Low-FODMAP, Gluten-free and Balanced) on Irritable Bowel Syndrome Symptoms and Health-Related Quality of Life. Nutrients, 11(7), p.1566.

14) Bellini, M. and Rossi, A., 2018. Is a low FODMAP diet dangerous?. Techniques in Coloproctology, 22(8), pp.569-571

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